The present invention relates to a computer system, and more particularly, to a method and a control apparatus for generating a power management signal for saving power of computer peripheral equipment, by selectively controlling a power supply or an operation state of the computer peripheral equipment, corresponding to a use state of the computer system.
Generally, computer peripheral equipment is each input/output apparatus, such as a monitor, a printer, a CD-ROM (Compact Disk-Read Only Memory), a plotter, etc., connected to a computer. Conventionally, such computer peripheral equipments can not be used as soon as the power supply is started. That is, when the power supply is started, it needs the time to perform operations such as an initiated operation and a preparatory heat operation or warm-up operation, though there is some difference according to each kind of equipment peculiarity. Accordingly, in case that a power is again supplied for re-using the relevant peripheral equipment of the computer, after cutting off the power in the midst of use of computer peripheral equipment, it is inconvenient to wait for the time it takes for the equipment to re-initialize or warm up again. The power supply state is maintained without a power interception in a state of use of the computer system even though the user does not use certain equipment, among the computer peripheral equipments, for a while. Especially with regard to the monitor being widely used as a computer display apparatus, the power is, always and mostly, supplied while the computer is being used. Therefore, unnecessary electric power has been wasted by the supply of the power to the monitor or other computer peripheral equipment even during non-use of the computer and especially a waste of power to the monitor greater than that to other peripheral equipments since the monitor drives a CRT (Cathode-Ray Tube) as a display device by using a high voltage.
Therefore, in the midst of computer system operation, in case that the computer system is not used by the user for a long time, the computer system senses it, and the power has been saved by cutting-off the power supply of the computer peripheral equipment or by controlling an operation state.
It is well known in the art to blank a data image being displayed on a monitor if no key input by the user has been sensed for a given time in the computer system, as, for example, disclosed in U.S. Pat. No. 5,059,961 for a "Screen Blanker For A Monitor Of A Computer System" by Te J. Cheng, et al., wherein the computer blanks the data image being displayed on the monitor if there is no input for a predetermined non-use time. After this time, the computer performs a blanking function by cutting off supply of a horizontal synchronizing signal and a vertical synchronizing signal to the monitor. When a key input is again generated by the user during the blanking function operation, the computer releases the blanking function of the monitor and again displays the data image displayed previously.
In U.S. Pat. No. 5,059,961, the life of the monitor may be lengthened by blanking a screen under a non-use state of the computer but the monitor still receives the power during the blanking period of the screen by blanking only the data image being displayed on the monitor. Accordingly, a waste of power is nearly similar to the waste of power during normal operation and a saving of power by such blanking function is tiny, and further even such tiny power saving is not applicable to other computer peripheral equipment.
Additionally, not only is there an inconvenience of installing software or special hardware inside of the computer for performing the screen blanking function, but there is also a problem of increased cost of the computer system. There is also a problem when utilizing the additional special hardware that the user can not voluntarily change the non-use time since the non-use time for performing the screen blanking function is predetermined and fixed, in accordance with embodying a sensing of use or non-use of the computer system, by the hardware.
The United States VESA (Video Electronics Standards Association) proposes a method for saving the power by managing the power of the monitor as one type of computer peripheral equipment corresponding to a use state of the computer system, in a "DPMS (Display Power Management Signaling) PROPOSAL" published and distributed by VESA on 26 Jan. 1993. If according to the "DPMS PROPOSAL", the computer as a host system selectively supplies or cuts off the horizontal synchronizing signal and/or the vertical synchronizing signal to the monitor for realizing mutually different power management states corresponding to a use state of the computer system, and the monitor performs the power management state corresponding to the input state of the horizontal synchronizing signal and the vertical synchronizing signal from the computer. The power management state is divided into an on state, a stand-by state, a suspend state and an off state, resulting in each of the horizontal synchronizing signal and the vertical synchronizing signal having a pulse or no pulse according to each power management state as shown in Table 1 below. That is, according to the power management state, all pulses of the horizontal synchronizing signal and the vertical synchronizing signal are output for the on state, only the pulse of the vertical synchronizing signal is output for the stand-by state, only the pulse of the horizontal synchronizing signal is output for the suspend state, and no pulses of the horizontal synchronizing signal and the vertical synchronizing signal are output for the off state. The power management state sequentially converts in the order of on state, stand-by state, suspend state and off state in response to a continuous time lapse of non-use of the computer system.
TABLE 1 ______________________________________ Power Management Horizontal Vertical Syn- State Synchronizing Signal chronizing Signal ______________________________________ On State Pulse Pulse Stand-by State No Pulse Pulse Suspend State Pulse No Pulse Off State No Pulse No Pulse ______________________________________
A "no pulse" state of each signal in above Table 1 means a state under 10 HZ of frequency of each signal and a "pulse" state of each signal means a state of normal synchronizing signal frequency of each signal.